Brush holder assembly and brush



Jan. l1, 1938. c. E. BERGER BRUSH HOLDER ASSEMBLY AND BRUSH Filed March3l, 1936 CLARE Patented jan. l1, 1938 UNITED STATES PATENT OFFICE BRUSHHOLDER ASSEMBLY AND BRUSH Application March 31, 1936, Serial No. 71,958

7 Claims.

This invention relates to brushes and brush holders for generators andparticularly for homopolar generators.

It is an object of this invention to provide a brush and means ofsupport therefor, whereby to support the brush in such a manner that itwill follow the contour of the commutator or slip ring, with which used,irrespective of eccentricity existing in the commutator or slip ring.

't is a further object of this invention to provide in such mechanism,means whereby the brush is supported for slight rocking movement about aguiding pin whereby the brush face remains in close contact with thecommutator or slip ring at all times, irrespective of irregularity ineccentricity of the surface of the commutator or slip ring with respectto the axis of rotation thereof.

It is further object of this invention to provide such a brush and brushholder as will carry a greater amount of current, without sparking, thana brush of the Same size and composition, mounted in a conventionalbrush holder.

It is a further object of this invention to provide means for supportinga brush for contact with the surface of a commutator or slip ring insuch manner as to apply resilient force at two spaced points on thebrush, which are widely separated from guiding means adapted to retainthe brush in position while allowing limited movement thereof toward andfrom the commutator or slip ring surface and limited rocking movementthereof with respect to the guiding means.

These and other advantages will appear from the following descriptiontaken in connection with the drawing.

In the drawing:

Figure l is an end elevational View of a brush and brush holderassembly, according to my invention;

Figure 2 is a plan View of the same.

Referring to the drawing in detail, the brush holder comprises a framehaving a rectangular portion I with a rectangular aperture 2 therein andoutwardly extending pintle arms 3 arranged in parallelism at oppositesides thereof. Extending from end to end of the frame and arrangedcentrally within the aperture 2 is a guiding pin 4 which is secured atopposite ends in the frame. Secured in apertures at the outer ends ofthe arms 3 at each side of the frame is a pintle 6 which is removablysecured in the apertures of the arms 3 by means of cotters 1 or anyother suitable means.

As shown in Figure 2, four arms 3 are arranged at each side of theframe, but it is, of course, to be understood that any number of sucharms may be used depending upon the number of brushes to be supported inthe brush holder. Rotatably secured between each pair of arms 3 to pivoton the pintle 6 is a brush arm 8 which has a central portion arrangedconcentrically with the axis of the pintle 6 and an annular flange 9 atone side thereof, which flange is equipped with notches Ill. Alsomounted in like manner on the pintle 6 between each pair of arms is athrust washer II. A coil spring I2 is disposed between each brush armand the adjacent thrust washer and has one end thereof formed into aloop I3 which is adapted to be hooked about the lower edge of one pintlearm 3. The other end thereof has a straight handle portion I4 formedthereon, which is adapted to be selectively received in one of the slotsIll in the annular iiange 9 of the brush arm.

As shown in the drawing, the righthand springs I2, when so disposed,urge the righthand brush arms 8 in a counterclockwise direction aboutthe righthand pintle 6. The lefthand brush arms 8 are supported in thesame manner for rotation about the lefthand pintle 6 and are adapted tobe swung in a clockwise direction about the pintle by means of the lefthand springs I2. Adapted to be supported within the rectangular aperture2 are three brushes I5 of rectangular cross section, each of which has alongitudinally disposed slot I6 therein and which extends from the lowerface I1 thereof throughout a part of the length and which slot I6 isadapted to receive the above described pin 4. The extreme ends of thebrush arms 8 are adapted to contact the top surface of the brush I5,which surface is preferably flat. The cross sectional area of therespective brushes is less than the corresponding portion of theaperture 2, whereby the brushes I5are adapted to be supported for slightpivotal movement about the pin 4 in the aperture 2. The points ofcontact of the extreme ends of the brush arms 8 with the top surface ofthe respective brushes I5 are spaced apart a substantial distance andthe extreme ends of the brush arms 8 are preferably of arcuate contour,as shown in the drawing, in order to produce substantial line contact ofthe arms with respect to the top faces of the brushes whereby tofacilitate the rocking movement thereof. This rocking movement isresisted by the springs I2 which resiliently urge the respective brusharms 8 against the top face of the brush. The lower face I1 of the brushI5 1s preferably arcuate and of a contour which is complementary to thesurface of the slip ring or commutator I8. The frame portion I has anupstanding bracket I9 at the rear end thereof, which is slotted at 2|]to provide means for attachment of the frame to the generator.

As will be clear from the drawing, the eifective tension of the springsI2 may be selectively adjusted by engaging the portion I4 of each withdesired slots ID in the annular flange 9. Bv this means, wear may becompensated for by increasing the eiective tension of the springs andnecessarily the position of the respective brush arms with respect tothe frame for a given eiective spring tension. Thus, where the desiredeffective spring tension for a new brush is that shown in Figure l andthe length of the "ish being also that shown in that gure, upon `llyreduce the effective spring tension, the portion ffl of the respectivesprings may be moved over into the second notch, whereby to compensatefor the wear in the brush.

While I have shown an assembly including mounting means for threebrushes, it is, of course, to be understood that the number of brushesused depends upon the commutator surface and that the drawing is, inthis respect, illustrative only and that I desire to comprehend withinmy invention the use of a single brush or any number thereof.

it is further to be understood that the springs for resiliently swingingthe arms 8 about the pintles may be replaced by other known resilientmeans such as known pneumatic and hydraulic devices or tension orcompression springs for performing the same function.

Furthermore, the arms 8 may be dispensed with and adjustable helicalflat springs having their ends provided with surfaces adapted to Contactthe brush in the same manner as do the ends of fhe arms 3 may besubstituted for the springs and arms as illustrated and described above.

t will be understood that the above described structure is merelyillustrative and that I desire to comprehend within my invention suchmodications as come Within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is:

l. In a brush assembly for a generator having a commutator, a brush,means to support said brush for relative sliding and rocking movementwith respect to a predetermined axis parallel to the axis of saidcommutator, and resilient means ior engaging said brush at oppositesides of said predetermined axis and urging said brush toward saidcommutator.

2. In a brush assembly for a generator having a slip ring, a brush,means to support said brush' for sliding and rocking movement relativeto a fixed axis parallel to the axis of the slip ring, and means forapplying resilient pressure to said brush at spaced points at oppositesides of said iixed axis to urge said brush resiliently toward said slipring and resiliently resist rocking movement thereof.

3. A brush assembly for a generator having a commutator comprising abrush supporting frame adapted to be secured to said generator adjacentsaid commutator, brush guide means in said frame including a guide pinparallel to the axis of said commutator, a brush having a longitudinalslot adapted to rockably and slidably engage said brush guide pin, andmeans on said frame for applying resilient pressure at spaced points onsaid brush at opposite sides of said slot to urge said brush toward saidcommutator.

4. A brush assembly for a generator having a slip ring comprising abrush supporting frame adapted to be secured to said generator adjacentsaid slip ring, brush guide means in said frame including a guide pinparallel to the axis of said slip ring, a brush having means adapted torockably and slidably engage said brush guide pin, and means on saidframe for applying resilient pressure at spaced points on said brush atopposite sides of said guide pin to urge said brush toward said slipring and resiliently resist rocking movement thereof about said pin,said last named means being adjustable to compensate for wear of saidbrush.

5. In combination, a brush having a slotted face, a holder for saidbrush comprising means for yieldingly urging the brush against thecommutator and a transverse pin disposed parallel to the axis of thecommutator arranged Within the slot in the brush about which pin thebrush is adapted to rock, said yielding means being adapted to engagesaid brush at points thereof disposed at opposite sides of said slot.

6. In combination, a transverse pin in a brush holder, a. slotted brushloosely mounted on said pin, said pin being located adjacent the openend of said slot, and yielding means engaging said brush at oppositesides of said pin for maintaining said brush on the pin against thecommutator, said pin being substantially parallel to the axis of saidcommutator.

7. In combination, with a commutator, of a brush having a commutatorengaging face with a slot opening into said face disposed radially ofsaid commutator and axially thereof, means mounted within said slotadapted to permit of a rocking movement of said brush without movementwith the commutator and yielding means for impelling said brush againstsaid commutator as guided by said means upon which it rocks.

CLARENCE E. BERGER.

